[PATCH V3] of: Set the DMA mask to 64 bits when dma_addr_t is 64-bits

[robherring2@gmail.com (Rob Herring)]

On 04/26/2013 03:31 PM, Laura Abbott wrote:
> Currently, of_platform_device_create_pdata always sets the
> coherent DMA mask to 32 bits. On ARM systems without CONFIG_ZONE_DMA,
> arm_dma_limit gets set to ~0 or 0xFFFFFFFFFFFFFFFF on LPAE based
> systems. Since arm_dma_limit represents the smallest dma_mask
> on the system, the default of 32 bits prevents any dma_coherent
> allocation from succeeding unless clients manually set the
> dma mask first. Rather than make every client on an LPAE system set
> the mask manually, account for the size of dma_addr_t when setting
> the coherent mask.
> 
> Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
> ---
>  drivers/of/platform.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index 0970505..5f0ba94 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -214,7 +214,7 @@ struct platform_device *of_platform_device_create_pdata(
>  #if defined(CONFIG_MICROBLAZE)
>  	dev->archdata.dma_mask = 0xffffffffUL;
>  #endif
> -	dev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
> +	dev->dev.coherent_dma_mask = DMA_BIT_MASK(sizeof(dma_addr_t) * 8);

This is going to change the mask from 32 to 64 bits on 64-bit powerpc
and others possibly. Maybe it doesn't matter. I think it doesn't, but
I'm not sure enough to apply for 3.10. So I'll queue it for 3.11.

Rob


>  	dev->dev.bus = &platform_bus_type;
>  	dev->dev.platform_data = platform_data;
>  
>